The 411 on Extreme Calorie-Restricted and Fasting Diets

If there’s one sure-fire way to lose weight, it’s cutting calories, eating healthy foods and working out. But what happens when you don’t just cut calories by a little bit, but instead periodically don’t eat or dramatically cut calories by 500 or more? While most health professionals and nutritionists wouldn’t tell the everyday average person to dip below getting 1,200 calories a day, there is a small group of people who follow low-calorie diets because they believe it keeps them healthy and prolongs their lives.

While severe calorie restriction (CR) has been shown to increase lifespan in animals, there hasn’t been much research on the practice in humans until now. Although much more research is needed on the quality of life while restricting calories, according to recent research from Washington University, people who drastic cut calories have lower core body temperatures than those who eat more. Having a lower core body temperature better allows your body to operate at maximum efficiency, according to a story on U.S. News and World Report. So what does this research mean to you, and should you try calorie restriction? The pros and cons are below!

The 411 on Extreme Calorie-Restricted and Fasting Diets


Periodic fasting or trying a low-calorie diet is extreme, but it can have benefits. Despite possibly improving health and lengthening your life span (jury is still out on that!), this kind of diet may also help you to eat healthier because you have to eat foods that are incredibly nutrient-dense to make sure that you were getting all of your vitamins and minerals (and take a multivitamin). Also, for those who are used to eating beyond fullness, fasting can help to reset hunger clues and give a stretched-out stomach a chance to reset to its normal size. When done in short-time frames, calorie-restricted diets can also result in sizable weight loss, thereby improving health and reducing strain on the body due to extra weight.


Because all the research isn’t in yet, there’s no real proven benefit to going on an extreme calorie-restricted diet. In addition, fasting and eating too little can be dangerous and may result in symptoms such as headache, fatigue, dizziness, low blood sugar and irritability, among others. Plus, it’s not much fun, and can leave you isolated from various social functions.

Who Is Best-Suited to Try It: Only those who have had this type of diet approved by their doctor or are under the guidance of a registered dietitian or other health professional should attempt this diet. Ideally, those trying periodic fasting would be in generally good overall health without suffering from emotional or binge eating. Those who do have a past with yo-yo dieting and fad dieting, along with those who are trying to lose weight for the first time, are not advised to try this diet and should instead focus their efforts on portion control, consistency and small changes in diet and an increase in exercise.

The bottom line? Always talk to your doctor or a registered dietitian before starting any substantial diet change, and listen to your body!

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